1. Field of the Invention
The present invention generally relates to apparatus and methods for providing breathable air to one or more safe havens within an underground mine from a source external to the mine.
2. General Background of the Invention
In the field of underground mining, the mineworkers, or miners, are always at risk of death from asphyxiation in any type of incident that interrupts the flow of breathable air into the mine and prevents them from exiting the mine before the breathable air in the mine is consumed. Under current regulations, each miner is required to carry one or more self-contained breathing apparatuses or self-contained self-rescuers (SCSRs). Under current regulations, the SCSRs carried by a miner are supposed to provide a sufficient supply of breathable air to either allow the miner to exit the mine or to make it to a safe haven within the mine. Safe havens are required whenever the working face of the mine is more than a specified number of feet from the mine entrance. Multiple safe havens become required when the mine face is located still farther away from the mine entrance.
Under current MSHA regulations, a safe haven must be capable of providing no less than 96 hours of breathable air for the number of miners expected to take shelter in the case of an emergency. This is intended to provide an adequate amount of time for the miners to be rescued. Generally breathable air is supplied by oxygen candles, bottled oxygen, bottled compressed air, or some other type of finite supply. Such finite supplies are far from ideal, however, because 96 hours does not always provide a sufficient amount of time. In many cases if it takes just a few short hours more than 96 for rescuers to reach the trapped miners, the miners in the safe haven will die. Bottles also present a problem in that they are bulky and take up a great deal of space. They must also be rotated and maintained to ensure they are properly charged and that their valves are operative.
Another problem created by these solutions is that it is not practical to provide enough breathable air to maintain a positive pressure inside the safe haven. Thus, it becomes necessary to make the safe haven airtight. Once this is done, then dealing with accumulated CO2 and CO become as problematic as providing breathable air in the first place. Typical solutions involve the use of various devices that absorb CO2 and CO, but once the absorption capacity of these devices is exceeded, these poisonous gases can quickly reach toxic concentrations in the atmosphere inside the safe haven. Maintenance of these CO2 and CO absorbing devices is also problematic because many of them have a shelf life and must be replaced periodically.
Having to create an airtight safe haven also presents a problem from the standpoint of what must be done if a miner arrives at the safe haven after it has been established and purged. If the miner is allowed to enter, the atmosphere in the safe haven will generally have to be purged again, consuming a great deal of the limited supply of breathable air, which could greatly reduce the amount of time that a breathable atmosphere can be maintained in the safe haven.
Yet another problem that can occur in a disaster is the unwanted intrusion of water in or around the safe haven, in between the safe haven and the mine entrance, or in between miners and the safe haven. Having a means of pumping this water out without requiring the pre-location of expensive permissible pumps would be beneficial.
Thus, what is needed is an apparatus and a method for establishing safe havens within a mine that will allow a virtually unlimited supply of breathable air to one or more safe havens in the mine. Said apparatus and method should also be capable of maintaining a positive air pressure relative to the air pressure in the mine within each of the safe havens so as to eliminate the need to scrub CO2 and CO from the atmosphere inside the safe havens.
What is also needed is a means of pumping water from undesirable areas in the mine without the use of costly permissible pumps.